CN107208306B

CN107208306B - Method and tool for cleaning single crystal pulling apparatus, and method for producing single crystal

Info

Publication number: CN107208306B
Application number: CN201680007916.7A
Authority: CN
Inventors: 冲田宪治
Original assignee: Sumco Corp
Current assignee: Sumco Corp
Priority date: 2015-02-03
Filing date: 2016-01-22
Publication date: 2020-07-14
Anticipated expiration: 2036-01-22
Also published as: WO2016125605A1; JP6428796B2; KR20170099950A; DE112016000581B4; TW201708628A; DE112016000581T5; CN107208306A; KR101937779B1; TWI591216B; US10000863B2; US20180016701A1; JPWO2016125605A1

Abstract

The invention provides a method for cleaning a single crystal pulling apparatus, which can remove foreign matters in a chamber and inhibit dislocation. In a method for cleaning a single crystal pulling apparatus according to the present invention, a dummy crucible including a dummy liquid surface that includes a liquid surface of a raw material melt in the crucible and a 1 st dummy ingot that includes a single crystal ingot pulled upward from the liquid surface of the raw material melt is prepared, and an inert gas is supplied in a state where the dummy crucible is provided in a chamber of the single crystal pulling apparatus that has been depressurized, and a flow of the inert gas affected by the dummy crucible is generated, so that foreign matter adhering to a wall surface of the chamber or a component in the chamber is detached.

Description

Method and tool for cleaning single crystal pulling apparatus, and method for producing single crystal

Technical Field

The present invention relates to a method for cleaning a single crystal pulling apparatus used for manufacturing a single crystal by the czochralski method (hereinafter, referred to as the CZ method), and more particularly, to a method for cleaning foreign matter such as small dust and dirt remaining in a chamber, which cannot be removed by normal removal cleaning. The present invention also relates to a cleaning tool used in the above cleaning method and a method for producing a single crystal by the above cleaning method.

Background

In the production of a silicon single crystal by the CZ method, various foreign substances such as vapor generated during pulling, abrasion powder of a wire rope, carbon dust generated by deterioration of a carbon module, quartz powder generated by chipping of a quartz crucible during cooling crystallization, and residual silicon powder adhere to various places in a single crystal pulling apparatus after the pulling process is completed. If the pulling process is carried out to the next pulling process without cleaning the foreign matter, the foreign matter is detached and attached to the growing single crystal, causing dislocation, and therefore, the chamber and the components in the chamber are detached and cleaned by wiping, vacuum cleaning, air blowing, or the like, every time the pulling process is finished.

However, since the structure of the single crystal pulling apparatus is complicated, it is difficult to completely sweep the corners of the single crystal pulling apparatus. Therefore, the occurrence of dislocation of the single crystal cannot be reduced by only the detachment cleaning.

In order to solve the above problem, patent document 1 proposes a cleaning device for cleaning the inner surface of the sub-chamber that is difficult to be manually cleaned and the wire rope hanging in the sub-chamber. Further, patent document 2 proposes a method of detaching and cleaning the single crystal pulling apparatus, and performing vacuum suction in the chamber after the assembly is set in the chamber and before the raw material is charged into the quartz crucible.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2001-348293

Patent document 2: japanese patent laid-open publication No. 2013-147406.

Disclosure of Invention

Problems to be solved by the invention

However, in the cleaning method described in patent document 2, fine foreign matters adhering to the inner wall of the chamber and components in the chamber cannot be sufficiently removed, and further improvement of the cleaning method is required.

Accordingly, an object of the present invention is to provide a method of cleaning a single crystal pulling apparatus, which can remove foreign matter in a chamber and suppress dislocation of a single crystal. It is another object of the present invention to provide a cleaning tool used in such a cleaning method. It is still another object of the present invention to provide a method for manufacturing a single crystal including such a cleaning method.

Means for solving the technical problem

In order to solve the above problem, a method for cleaning a single crystal pulling apparatus according to claim 1 of the present invention includes: a dummy crucible is prepared which includes a dummy liquid surface which is a surface of a raw material melt in the crucible and a 1 st dummy ingot which is a surface of a single crystal ingot pulled upward from the surface of the raw material melt, and a gas is supplied in a depressurized chamber of a single crystal pulling apparatus, and the gas is flowed under the influence of the dummy crucible, so that foreign substances attached to a wall surface of the chamber or components in the chamber are removed.

According to the present invention, the structure in the chamber during the single crystal pulling is reproduced in a simulated manner, and a strong flow and turbulence of the gas are intentionally generated, so that foreign matter adhering to the wall surface of the chamber or components in the chamber can be detached, and foreign matter such as small dust and dirt remaining in the chamber, which cannot be removed cleanly by conventional removal cleaning, can be removed in advance. Therefore, detachment of foreign matter in the subsequent pulling step can be reduced, and the occurrence rate of dislocation of the single crystal due to adhesion of foreign matter can be reduced.

In the present invention, it is preferable that the single crystal pulling apparatus includes: a rotary support shaft that supports the crucible in the chamber so as to be able to ascend and descend; and a heat shield disposed above the rotation support shaft, wherein the cleaning step is performed by adjusting the height of the dummy crucible so that a 1 st gap width between the dummy liquid surface and the lower end of the heat shield is substantially equal to a 2 nd gap width between the liquid surface of the raw material melt and the lower end of the heat shield in the actual single crystal pulling step, that is, so that the gap width that can be used in the actual single crystal pulling step is obtained. In this way, by reproducing the narrow gap width between the heat shield and the liquid surface of the raw material melt in the cleaning step, a strong flow and turbulence of the gas can be reproduced. Therefore, the foreign matter detached at the time of actual pulling can be removed in advance, and the occurrence rate of dislocation of the single crystal due to adhesion of the foreign matter can be reduced.

In the cleaning method according to the present invention, it is preferable that the dummy crucible is swung up and down in the cleaning step. In this way, by vertically swinging the dummy crucible, the flow of the gas in the chamber can be intentionally changed. Therefore, dust generation during actual pulling can be prevented, and the occurrence rate of dislocation of single crystal due to adhesion of foreign matter can be reduced.

Preferably, the 1 st dummy ingot includes a shoulder portion having a gradually increasing diameter and a body portion having a constant diameter, and the 1 st dummy ingot is raised together with the dummy crucible such that a lower end of the shoulder portion moves from a 1 st height position below a lower end of the heat shield to a 2 nd height position above the lower end of the heat shield when the dummy crucible is lifted. When the lower end of the shoulder portion (the upper end of the body portion) is at the same height as the lower end of the heat shield, the flow of the gas is rapidly increased, and therefore, the foreign matter in the chamber can be removed.

In the present invention, it is preferable that the dummy crucible is made of resin. When the entire dummy crucible including the dummy liquid surface and the 1 st dummy ingot is made of resin, it can be manufactured at a very low cost and is easy to handle. In addition, when the dummy crucible is a white material, black foreign matter such as carbon dust can be captured by visual observation when the black foreign matter falls off and adheres to the dummy crucible, and the dummy crucible can also function as a foreign matter collection/confirmation device.

In the cleaning method according to the present invention, it is preferable that a 2 nd dummy ingot which is a single crystal ingot is prepared, and in the cleaning step, gas is supplied in a state where the 2 nd dummy ingot is suspended in the chamber, and a flow of the gas affected by the 2 nd dummy ingot is generated so that foreign matter adhering to a wall surface of the chamber or a component in the chamber is detached. According to the present invention, the structure in the chamber during the single crystal pulling is reproduced, and a strong flow and turbulence of the gas are intentionally generated, so that foreign matter adhering to the wall surface of the chamber or components in the chamber can be detached, and small foreign matter such as dust and dirt remaining in the chamber, which cannot be removed cleanly by conventional removal cleaning, can be removed in advance. Therefore, detachment of foreign matter in the subsequent pulling step can be reduced, and the occurrence rate of dislocation of the single crystal due to adhesion of foreign matter can be reduced.

In the cleaning method according to the present invention, it is preferable that the cleaning step is performed in a state where the 2 nd dummy ingot and the 1 st dummy ingot are connected to each other. By setting as above, it is possible to reproduce a long single crystal ingot in the chamber and to reproduce a strong flow and turbulence of the gas generated in the actual pulling process. Therefore, the foreign matter remaining in the chamber can be removed in advance, and the occurrence rate of dislocation of the single crystal due to adhesion of the foreign matter can be reduced.

In the present invention, it is preferable that the chamber has: a main chamber; and a sub-chamber connected to an upper opening of the main chamber, and performing the cleaning process in a state where the 2 nd dummy ingot is disposed in the sub-chamber. This makes it possible to reproduce a narrow gap width between the sub-chamber and the single crystal ingot, and to generate a strong flow of gas in the sub-chamber. Therefore, the foreign matter detached from the sub-chamber during actual pulling can be removed in advance, and the occurrence rate of dislocation of the single crystal due to adhesion of the foreign matter can be reduced.

In the cleaning method according to the present invention, it is preferable that the cleaning step is performed in a state in which the 2 nd dummy ingot is vertically oscillated independently of the dummy crucible. By oscillating the 2 nd dummy ingot up and down, the flow of gas can be intentionally changed. Therefore, the amount of dust generated during actual pulling can be reduced, and the occurrence rate of dislocation of single crystal due to adhesion of foreign matter can be reduced.

In the present invention, it is preferable that the single crystal pulling apparatus further includes a wire rope which is disposed coaxially with the rotation support shaft and has a hook attached to a distal end portion thereof, a ring fitting is attached to a distal end portion of the 2 nd dummy ingot, and the 2 nd dummy ingot is connected to a lower end portion of the wire rope by engaging the hook with the ring fitting and by allowing the engagement to take a play. Thus, when the 2 nd dummy ingot is mounted on and connected to the 1 st dummy ingot, the 2 nd dummy ingot can be lifted and lowered together with the 1 st dummy ingot while avoiding the occurrence of bending of the wire rope.

In the present invention, it is preferable that the 2 nd dummy ingot is made of resin. Thus, the 2 nd dummy ingot can be produced at low cost, and the installation is easy to handle. In the case where the 2 nd dummy ingot is a white material, black foreign matter such as carbon dust can be captured by visual observation when the foreign matter adheres thereto, and the dummy ingot can also function as a foreign matter collection/confirmation device.

The method for cleaning a single crystal pulling apparatus according to claim 2 of the present invention is characterized by comprising the following cleaning steps: a dummy ingot which is a single crystal ingot is prepared, and a gas is supplied in a state where the dummy ingot is suspended in a depressurized chamber of a single crystal pulling apparatus, and a flow of the gas affected by the dummy ingot is generated to detach foreign matter adhering to a wall surface of the chamber or components in the chamber.

In the cleaning method according to claim 2 of the present invention, it is preferable that the dummy ingot is made of resin, and the cleaning step is performed with the temperature in the chamber set to normal temperature.

In the present invention, it is preferable that the dummy ingot has: a shoulder portion having a gradually increasing diameter; and a body portion having a constant diameter below the shoulder portion, wherein the dummy ingot is pulled up in the cleaning step so that a lower end of the shoulder portion passes through an opening at a lower end of a heat shield provided above the crucible. When a dummy ingot is connected to the lower end of a pulling shaft for pulling a single crystal and the lower end of the shoulder portion (the upper end of the body portion) is moved from a height position below the lower end of the thermal shield to a height position above the lower end of the thermal shield, the flow of gas is rapidly increased when the lower end of the shoulder portion is at the same height as the lower end of the thermal shield, and therefore, foreign matter in the chamber can be removed.

In the cleaning method according to claim 2 of the present invention, a crucible for supporting the raw material melt may be provided in the chamber, and the cleaning step may be performed in the chamber at a high temperature in which the raw material melt is actually stored in the crucible. In this case, it is preferable that the crucible is composed of quartz, and the dummy ingot is composed of at least one material selected from the group consisting of silicon, quartz, carbon, silicon carbide, and molybdenum. In this way, by performing cleaning at a high temperature immediately before the single crystal pulling process, foreign substances in the chamber can be sufficiently removed.

In the present invention, it is preferable that the height of the crucible is adjusted so that the height of the crucible at the time of starting the cleaning step is lower than the height of the crucible at the time of starting the single crystal pulling step. In the cleaning step, preferably, when the lower end of the shoulder portion is at the same height as the lower end of the heat shield, the height of the crucible is adjusted so that a 1 st gap width between the liquid surface of the raw material melt and the lower end of the heat shield is substantially equal to a 2 nd gap width between the liquid surface of the raw material melt and the lower end of the heat shield in the actual single crystal pulling step, that is, so that a gap width that can be used in actual single crystal pulling is obtained. By setting in this manner, the flow rate of the gas introduced into the chamber can be further increased. In particular, by reproducing conditions as close as possible to those in the actual single crystal pulling step, foreign matter in the chamber can be reliably removed.

In the cleaning method according to claim 2 of the present invention, it is preferable that the cleaning step is performed after the raw material is additionally charged into the crucible. In this case, it is preferable that the raw material is additionally charged into a charging pipe connected to a lower end of a pulling shaft for pulling the single crystal, and then the charging pipe is replaced with the dummy ingot, and then the cleaning step is performed. When the supplementary raw material is added, or when the raw material is re-charged, or when the raw material used in a new single crystal pulling step is additionally charged, the fine powder of the raw material diffuses in the chamber and adheres thereto, and falls off in the pulling step, which may cause dislocation of the single crystal. However, by performing the final cleaning after the additional input and before the pulling step, the occurrence rate of dislocation of the single crystal can be further reduced.

In the present invention, it is preferable that the dummy ingot has a hollow structure. When the dummy ingot is in a block shape, cracks or fractures easily occur due to thermal expansion in the high-temperature chamber. However, when the dummy ingot has a hollow structure, heat accumulation can be suppressed to prevent occurrence of cracks or fractures.

A cleaning tool for a silicon single crystal pulling apparatus according to claim 3 of the present invention is characterized by comprising: a dummy crucible which is a dummy crucible used for pulling a single crystal; a dummy liquid level which is a level of the raw material melt in the crucible; and a 1 st dummy ingot which is a single crystal ingot pulled upward from the liquid surface of the raw material melt.

The cleaning tool according to the present invention preferably further includes a 2 nd dummy ingot which is a single crystal ingot, wherein an upper end portion of the 1 st dummy ingot has a conical projection, and a lower end portion of the 2 nd dummy ingot has a conical recess which is fittable with the upper end portion of the 1 st dummy ingot. According to this configuration, the 2 nd dummy ingot and the 1 st dummy ingot can be connected to each other, and a long single crystal ingot can be reproduced in the chamber.

A cleaning tool according to a single crystal pulling apparatus of claim 4 of the present invention is characterized by being composed of a dummy ingot which is a single crystal ingot and has a conical recess at a lower end portion thereof. According to the present invention, the same environment as that in actual pulling can be reproduced using a dummy ingot, and strong flow and turbulence of gas can be generated in the chamber to remove foreign matter detached in actual pulling in advance, thereby reducing the occurrence of dislocation of a single crystal due to adhesion of foreign matter. Further, by connecting dummy ingots, a long single crystal ingot can be reproduced in the chamber.

A method for producing a single crystal according to aspect 5 of the present invention includes: disassembling and cleaning a chamber of a single crystal pulling apparatus and components in the chamber; performing final cleaning of the single crystal pulling apparatus by the cleaning method after the detachment cleaning; and pulling up the single crystal by using the single crystal pulling apparatus after the final cleaning is finished.

Effects of the invention

According to the present invention, it is possible to provide a cleaning method of a single crystal pulling apparatus capable of removing foreign matter in a chamber which cannot be removed by normal removal cleaning and suppressing dislocation of a single crystal. Further, according to the present invention, a cleaning tool used in such a cleaning method can be provided. Further, according to the present invention, it is possible to provide a method for producing a single crystal, in which the yield of the single crystal is improved by using such a cleaning method.

Drawings

Fig. 1 is a schematic cross-sectional view showing the structure of a single crystal pulling apparatus 1 to be cleaned according to the present invention.

Fig. 2 is a sectional view for explaining a cleaning method (final cleaning step) of the single crystal pulling apparatus 1 according to embodiment 1 of the present invention.

Fig. 3 is a schematic perspective view showing the structure of the dummy crucible 30 and the dummy ingot 40.

Fig. 4 is a sectional view for explaining the function of the dummy crucible 30.

Fig. 5 is a diagram for explaining an example of the arrangement of the dummy crucible 30 and the 2 nd dummy ingot 40 during cleaning.

Fig. 6 is a diagram for explaining another example of the arrangement of the dummy crucible 30 and the 2 nd dummy ingot 40 during cleaning.

Fig. 7 is a sectional view for explaining a cleaning method of the single crystal pulling apparatus 1 according to embodiment 2 of the present invention.

Fig. 8 is a sectional view for explaining a cleaning method of the single crystal pulling apparatus 1 together with fig. 7.

Fig. 9 is a sectional view for explaining a cleaning method of the single crystal pulling apparatus 1 together with fig. 7 and 8.

Fig. 10 is a sectional view for explaining a cleaning method of the single crystal pulling apparatus 1 together with fig. 7 to 9.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in fig. 1, this single crystal pulling apparatus 1 is an apparatus for manufacturing a silicon single crystal for semiconductor by the CZ method, and includes a chamber 10, a heat insulator 11 disposed inside the chamber 10, a base 13 for supporting a quartz crucible 12 accommodated in the chamber 10, a rotating support shaft 14 for supporting the base 13 so as to be able to be raised and lowered, a heater 15 disposed so as to surround the periphery of the base 13, a heat shield 16 disposed above the base 13, a wire rope 17 for pulling a single crystal disposed above the base 13 and coaxially with the rotating support shaft 14, and a wire rope winding mechanism 18 disposed above the chamber 10.

The chamber 10 is composed of a main chamber 10A and a sub-chamber 10B connected to an upper opening of the main chamber 10A, and the quartz crucible 12, the base 13, the rotation support shaft 14, the heater 15, and the heat shield 16 are provided in the main chamber 10A. The winding mechanism 18 is disposed above the sub-chamber 10B, the wire 17 extends downward from the winding mechanism 18 through the sub-chamber 10B, and the end portion of the wire 17 extends to the internal space of the main chamber 10A. Fig. 1 shows a state where a silicon single crystal 2 is suspended from the distal end portion of a wire rope 17.

The heat shield 16 is provided to suppress temperature fluctuation of the silicon melt 3, form an appropriate hot zone in the vicinity of the crystal growth interface, and prevent heating of the silicon single crystal 2 by radiant heat from the heater 15 and the quartz crucible 12. The heat shield 16 is a carbon member covering an upper region of the silicon melt 3 except for the pulling path of the silicon single crystal 2, and particularly has an inverted truncated cone shape with an opening size increasing from a lower end toward an upper end. The opening diameter of the lower end of the heat shield 16 is larger than the diameter of the silicon single crystal 2, thereby ensuring the pulling path of the silicon single crystal 2. Further, since the opening diameter of the lower end of the heat shield 16 is smaller than the diameter of the quartz crucible 12 and the lower end of the heat shield 16 is positioned inside the quartz crucible 12, the heat shield 16 does not interfere with the quartz crucible 12 even when the upper edge of the quartz crucible 12 is raised above the lower end of the heat shield 16.

In the above configuration, in the step of pulling up the silicon single crystal, first, the quartz crucible 12 is provided in the susceptor 13, the silicon material is filled in the quartz crucible 12, and the seed crystal is attached to the end portion of the wire rope 17. Next, the silicon raw material is heated by the heater 15 to generate the silicon melt 3, and the seed crystal is lowered to be brought into contact with the silicon melt 3. Then, the seed crystal is slowly raised while rotating the quartz crucible 12, thereby growing the silicon single crystal 2 having a substantially cylindrical shape.

In the single crystal pulling, the inside of the chamber 10 is maintained in a constant reduced pressure state. Argon gas is supplied from an inlet port 19A provided in the upper part of the sub-chamber 10B and is discharged from an outlet port 19B provided in the lower part of the main chamber 10A, whereby a flow of argon gas indicated by a broken-line arrow is generated in the chamber 10, and the flow (gas flow) constantly changes depending on the growth state of the single crystal. The atmosphere gas in the chamber 10 is not limited to argon gas, and other inert gases may be used.

The diameter of the silicon single crystal 2 is controlled by controlling the pulling rate and the temperature of the heater 15. In the growth of the silicon single crystal 2, after a neck portion is formed in which the crystal diameter is reduced to be thin, the crystal diameter is expanded in a conical shape to form a shoulder portion. When the single crystal is grown to a predetermined diameter, pulling is continued with a constant diameter to form a body portion, and when pulling is completed, the diameter is reduced to be thinner to form a tail portion, and the tail portion is finally separated from the liquid surface. Thus, a silicon single crystal ingot having a shoulder and a body is completed.

The structure and operation of the single crystal pulling apparatus 1 are explained above. Next, a method of cleaning the single crystal pulling apparatus 1 will be described. As the cleaning of the single crystal pulling apparatus 1, there are removal cleaning and final cleaning after the removal cleaning. The disassembly and cleaning process comprises the following steps: after the batch processing is completed, the apparatus is disassembled to clean each part and remove powder, deposits, and the like adhering to the inner wall of the chamber 10 and the components in the chamber 10.

On the other hand, the final cleaning is a cleaning process performed after such removal cleaning and before the start of the next pulling process of the silicon single crystal. By this final cleaning, foreign matters in the chamber 10 that cannot be removed cleanly in the detaching cleaning can be removed.

As shown in fig. 2, in the final cleaning, two kinds of cleaning tools are used in order to reproduce the environment in the chamber 10 in the single crystal pulling. One is a dummy crucible 30 imitating the shape of the actual quartz crucible 12, and the other is a dummy ingot 40 imitating the shape of a single crystal ingot.

As shown in fig. 3, the dummy crucible 30 is a resin member having substantially the same size (diameter) as the quartz crucible 12 actually used. The dummy crucible 30 may be similar in shape to the quartz crucible 12 actually used, and does not require strict conformity. A dummy liquid surface 31 which simulates the liquid surface of the silicon melt 3 in the dummy crucible 30 is formed integrally with the dummy crucible 30, and a dummy ingot 32 (1 st dummy ingot) which simulates the shape of a silicon single crystal pulled upward from the liquid surface of the silicon melt 3 is formed integrally with the dummy liquid surface 31. That is, the dummy crucible 30 is a single structure including the dummy liquid surface 31 and the dummy ingot 32.

The dummy crucible 30 is directly provided at the upper end portion of the rotary support shaft 14. I.e. without the use of a base 13. This is because the quartz crucible 12 softened at a high temperature in the actual pulling process needs to be supported by the susceptor 13, but the cleaning process is performed at a normal temperature, and it is not necessary to consider deformation of the dummy crucible 30. Further, the provision of the base 13 can be omitted, thereby simplifying the preparation work of the cleaning process. In addition, the bottom of the dummy crucible 30 must be shaped to be able to be set on the rotating support shaft 14.

The dummy ingot 40 (2 nd dummy ingot) is a resin member having substantially the same diameter as the silicon single crystal ingot actually pulled up, and has a shoulder portion 40a having a diameter gradually increased downward and a body portion 40b having a constant diameter. A ring fitting 40d is provided at the upper end of the shoulder 40a, and the dummy ingot 40 is suspended to be movable up and down by engaging a hook 17a provided at the distal end of the wire rope 17 with the ring fitting 40 d. Further, since the engagement between the hook 17a and the ring metal fitting 40d is provided with a play, a large deflection of the wire rope 17 can be avoided in a state where a dummy ingot 40 described later is mounted on the dummy ingot 32.

The dummy ingot 40 can be fitted to the dummy ingot 32 integrated with the dummy crucible 30. Since the upper end portion of the dummy ingot 32 has a conical convex portion 32a (shoulder portion) and the lower end portion of the dummy ingot 40 has a conical concave portion 40c, the dummy ingot 32 can be fitted only by lowering the dummy ingot 40. Even when the dummy ingot 40 swings due to the wind pressure of the argon gas, it can be connected to the dummy ingot 32 while correcting the positional deviation of the central axis thereof in a self-alignment manner. Then, by connecting the dummy ingot 40 to the dummy ingot 32, a long single crystal can be reproduced (see fig. 5).

In the present embodiment, 2 dummy ingots were used. The dummy ingot 32 is integrated with the dummy crucible 30, and serves to impart a change in the flow of argon gas below the heat shield 16. The dummy ingot 40 acts to change the flow of the argon gas above the heat shield 16, and changes the flow of the argon gas by narrowing the opening area of each portion in the chamber 10 in a state where the single crystal is actually pulled.

The material of the dummy crucible 30 and the dummy ingot 40 is not particularly limited, but a resin such as polypropylene is preferably used. The resin is easy to process and can be produced at low cost. In the case of a white material, for example, when black foreign matter such as carbon dust falls and adheres to the dummy ingot 40 and the dummy crucible 30, the foreign matter can be captured by visual observation, and can also function as a foreign matter collection/confirmation device.

In the final cleaning step, after the dummy crucible 30 and the dummy ingot 40 are set in the chamber 10, argon gas of a predetermined flow rate is supplied into the chamber 10, and the inside of the chamber 10 is set to an argon atmosphere at normal temperature and reduced pressure, the argon gas is supplied from the gas inlet 19A provided in the upper portion of the sub-chamber 10B, and is discharged from the gas outlet 19B provided in the lower portion of the main chamber 10A through the sub-chamber 10B and the main chamber 10A, the pressure in the chamber 10 is preferably set to 20 to 30Torr, the supply amount of the argon gas can be set to 130L/min, for example, the pressure in the chamber 10 is measured by a pressure gauge, and the discharge amount of the argon gas discharged from the gas outlet 19B is controlled so that the pressure in the chamber 10 becomes constant.

In the present embodiment, the final cleaning is performed at normal temperature. The temperature in the chamber 10 may be raised to the same temperature as in the actual single crystal pulling process, and the cleaning may be performed at a high temperature, but it takes time to raise the temperature in the chamber 10 or cool the chamber after the cleaning, which is not efficient. Further, the dummy ingot 40 and the dummy crucible 30 cannot be made of resin. For this reason, the final cleaning is preferably performed at normal temperature.

In the final cleaning, the room temperature/reduced pressure state in the chamber is maintained for a certain time. The cleaning time is not particularly limited, but is preferably about 2 to 8 hours.

In the final cleaning, the dummy crucible 30 is lifted to be close to the heat shield 16, and the dummy ingot 32 is inserted into the opening 16a of the heat shield 16. At this time, the dummy crucible 30 may be lifted while being rotated, or may be lifted without being rotated.

It is known that disturbance of the single crystal often occurs when the shoulder portion of the single crystal enters the opening portion of the heat shield 16. This is considered to be because the shoulder portion of the single crystal enters the opening portion 16a of the heat shield 16, which is wide until now, and the opening area becomes narrow, and the flow rate of the argon gas is increased due to the single crystal becoming a resistance that impedes the flow of the argon gas, and foreign matter that has adhered to the wall body or the component of the chamber 10 until now detaches and adheres to the single crystal. Therefore, in the final cleaning, an environment in which foreign substances are easily removed is reproduced by intentionally inserting the shoulder portion of the dummy ingot into the opening portion of the heat shield 16.

The diameter of the opening 16a of the heat shield 16 is slightly larger than the diameter of the single crystal. Initially, the opening area is wide, and therefore the argon gas flows relatively smoothly, but if the shoulder portion of the dummy ingot 32 enters the opening 16a due to the rising of the dummy crucible 30, the opening area is sharply narrowed, and the flow velocity of the argon gas trying to pass through the narrow gap between the dummy crucible 30 and the heat shield 16 is increased. This changes the airflow in the chamber 10, and makes it easy to generate turbulence, so that fine foreign matters attached to corners and recesses in the chamber 10 can be detached and lifted, and the foreign matters can be removed by exhausting together with the airflow.

If the dummy crucible 30 is lifted, not only the gap between the heat shield 16 and the dummy ingot 32 but also the gap between the heat shield 16 and the upper end of the edge of the dummy crucible 30 becomes narrow. Therefore, the flow rate of the argon gas to pass through the narrow gap between the thermal shield 16 and the dummy crucible 30 is further increased, and the gas flow in the chamber 10 is changed, which tends to generate turbulence.

When the dummy crucible 30 is lifted up to approach the heat shield 16, the gap width (1 st gap width) G between the dummy liquid surface 31 and the lower end of the heat shield 16 is preferably substantially equal to the gap width (2 nd gap width) between the liquid surface of the silicon melt 3 in the quartz crucible 12 and the lower end of the heat shield 16 in the actual single crystal pulling step, that is, it is preferably adjusted so as to be a gap width that can be used in the actual single crystal pulling, and it is more preferable to maintain this state for a certain period of time. With such a setting, the flow velocity of the argon gas that attempts to pass through the narrow gap between the thermal shield 16 and the dummy liquid surface 31 is further increased, and therefore the gas flow in the chamber 10 changes, and turbulence is likely to occur. Therefore, foreign matter adhering to the inside of the chamber 10 can be detached and lifted, and can be exhausted together with the airflow to remove the foreign matter.

Fig. 5 is a diagram for explaining an example of arrangement of the dummy crucible 30 and the dummy ingot 40 during cleaning.

As shown in fig. 5, a dummy ingot 40 may be coupled to the dummy crucible 30. The dummy crucible 30 and the dummy ingot 40 are not connected to each other immediately after the dummy crucible is set, but the dummy ingot 40 is lowered to connect the two to each other, whereby a longer single crystal can be reproduced in the chamber 10. In the cleaning, it is preferable to maintain the dummy ingot 40 and the dummy crucible 30 in a coupled state for a certain period of time. By setting in this manner, a state closer to the actual pulling can be reproduced, and the flow and flow rate of the argon gas can be further changed.

In addition, in the present embodiment, since the engagement between the hook 17a and the ring metal fitting 40d is provided with a play, when the dummy ingot 40 is mounted on the dummy ingot 32 and connected, the dummy ingot 40 can be lifted and lowered together with the dummy ingot 32 while avoiding a large deflection of the wire rope 17.

In the final cleaning, it is also preferable to swing the dummy crucible 30 up and down. At this time, the dummy ingot 40 may be connected to the dummy crucible 30 or may be separated from the dummy crucible 30. In short, the dummy crucible 30 is moved up and down to further change the gas flow in the chamber 10, so that a turbulent flow of argon gas can be generated in the chamber 10, and foreign substances in the chamber 10 can be removed.

In the final cleaning, it is also preferable to separate the dummy ingot 40 from the dummy crucible 30 and swing the dummy ingot 40 up and down independently of the dummy crucible 30. In this case, only the dummy ingot 40 may be moved up and down by fixing the position of the dummy crucible 30 in the height direction, the dummy crucible 30 may be moved up and down by fixing the dummy ingot 40, or both may be moved up and down. When the dummy ingot 40 is separated from the dummy crucible 30, the airflow in the chamber 10 can be changed by largely changing the position in the height direction of the dummy ingot 40, and foreign matter that cannot float up when the dummy ingot 40 is merely stopped at a certain position can float up.

Fig. 6 is a diagram for explaining another example of the arrangement of the dummy crucible 30 and dummy ingot 40 during cleaning.

As shown in fig. 6, dummy ingots 40 may also be disposed in the sub-chamber 10B. When the dummy ingot 40 is located in the sub-chamber 10B, the airflow velocity becomes strong by the argon gas passing through the narrow gap between the dummy ingot 40 and the inner wall surface of the sub-chamber 10B. The sub-chamber 10B has a member having an uneven surface such as a gate valve and a sensor at an upper portion thereof, and foreign matter is likely to adhere thereto, but the foreign matter in the sub-chamber 10B can be removed because the airflow in the sub-chamber 10B is increased. Further, since the airflow speed in the main chamber 10A becomes high due to the high airflow speed, turbulence is likely to occur, and therefore, foreign matter in the main chamber 10A can be removed.

After the final cleaning is completed, the atmosphere is opened to the chamber 10, the dummy crucible 30 and the dummy ingot 40 are taken out, the susceptor 13 and the quartz crucible 12 are provided on the rotary support shaft 14, and the silicon material is filled into the quartz crucible 12. Then, the conventional single crystal pulling step described above is performed. As described above, in the present embodiment, since the final cleaning is performed, the probability of occurrence of dislocation due to the influence of foreign matter remaining in the chamber 10 can be reduced in the single crystal pulling step.

As described above, according to the cleaning method of the single crystal pulling apparatus 1 of the present embodiment, the structure in the chamber during pulling of a single crystal is reproduced, and strong flow and turbulent flow of argon gas generated in the chamber are artificially generated due to the presence of the quartz crucible and the single crystal ingot, whereby the flow rate of the inert gas is intentionally changed, and foreign matters adhering to corners and recesses in the chamber are detached and removed in advance, so that the dust generation amount in the subsequent pulling process can be reduced, and the occurrence rate of dislocation of a single crystal due to adhesion of foreign matters can be reduced.

Fig. 7 to 10 are sectional views for explaining a cleaning method of a single crystal pulling apparatus according to embodiment 2 of the present invention.

As shown in fig. 7, this cleaning method is characterized in that cleaning using a dummy ingot 50 is performed in a state where a silicon melt 3 is stored in a quartz crucible 12 immediately before a single crystal pulling step is started. Therefore, unlike embodiment 1, a dummy crucible is not provided in the chamber 10 but a quartz crucible 12 actually used in the single crystal pulling process is provided, the quartz crucible 12 is heated by the heater 15, and the chamber 10 is maintained at a high temperature.

The cleaning method according to embodiment 1 is considered to be effective as a cleaning method before starting the single crystal growth process. However, for example, as shown in fig. 8, when the silicon raw material 5 is additionally charged into the quartz crucible 12 by using the charging pipe 60, the fine silicon powder attached to the surface of the charging pipe 60 is detached and floated in the chamber 10, or when the silicon raw material in the charging pipe 60 is dropped and charged into the quartz crucible 12, the fine silicon powder attached to the inner surface of the charging pipe 60 and the silicon raw material 5 floats and adheres to the in-furnace structure such as the heat shield 16, which causes dislocation of the single crystal. Therefore, in the present embodiment, cleaning using dummy ingots is performed in the chamber 10 at a high temperature immediately before the single crystal pulling process is started, so that further purging in the chamber 10 is realized.

Since the chamber 10 is at a high temperature and the silicon melt 3 is held in the quartz crucible 12, the dummy ingot 50 used for cleaning needs to have heat resistance and not contaminate the silicon melt 3. Therefore, the material of the dummy ingot 50 is preferably silicon, quartz, carbon, silicon carbide (SiC), carbon coated with SiC on the surface, molybdenum, or the like. As the dummy ingot 50, for example, a dummy ingot in which a silicon single crystal ingot not processed as a wafer product is processed into a predetermined shape after being pulled by a single crystal pulling apparatus of the same type as the cleaning object can be used. By using an undeproduceable silicon single crystal ingot as the dummy ingot 50 in this manner, the labor for producing the dummy ingot from the beginning can be omitted, and resources can be effectively used.

The dummy ingot 50 may have a shoulder portion 50a having a diameter gradually increasing from top to bottom and a body portion 50b having a diameter kept constant below the shoulder portion 50a, similarly to the shape of the tip side of the silicon single crystal ingot actually grown by the CZ method. The dummy ingot 50 may have a hollow structure having a cavity therein, or may be a block having no cavity. When the dummy ingot 50 is a hollow structure, an opening may be formed at the bottom thereof. When the dummy ingot has a hollow structure, heat accumulation can be suppressed to prevent occurrence of cracks or fractures. In the cleaning step, the dummy ingot 50 cannot come into contact with the silicon melt 3, and therefore the length of the body portion 50b of the dummy ingot 50 needs to be set in consideration of the height of the liquid level of the silicon melt in the quartz crucible 12.

Next, the cleaning process will be described with reference to fig. 7 to 10.

First, as shown in fig. 8, the silicon raw material 5 is additionally charged using a charging pipe 60. The additional charge may be performed for pulling up a silicon single crystal ingot after the second stage in a so-called multi-stage pulling method. In the multi-step pulling method, after a silicon single crystal is pulled, a silicon raw material is additionally supplied into the same quartz crucible to melt, and the silicon single crystal is pulled from the obtained silicon melt, and a plurality of silicon single crystals are produced from one quartz crucible by repeating the raw material supply step and the single crystal pulling step. According to the multi-stage crystal pulling method, the raw cost of the quartz crucible per one silicon single crystal can be reduced. Further, since the frequency of removing the chamber and replacing the quartz crucible can be reduced, the work efficiency can be improved.

The additional charge may be performed to replenish the silicon raw material in the quartz crucible in the so-called single crystal pulling method. In this case, polycrystalline silicon previously charged into the quartz crucible 12 at normal temperature is heated in the chamber 10 to generate the silicon melt 3, and then the silicon raw material is additionally supplied. According to this method, an elongated silicon single crystal can be pulled, and the work efficiency can be improved.

The input tube 60 is a cylindrical quartz glass container having an openable/closable bottom cover 61. The charging pipe 60 is suspended from the lower end of the wire rope 17, and the charging pipe 60 is lowered from a position in the sub-chamber 10B to approach the vicinity of the melt surface. Then, the additional silicon raw material 5 in the charging tube 60 drops and is charged into the quartz crucible 12 by opening the bottom cover 61.

As described above, in the additional step of the silicon raw material using the charging pipe 60, the fine silicon powder is likely to adhere to the wall surface of the chamber 10 and the structural object in the furnace such as the heat shield 16, which may cause dislocation of the single crystal. Therefore, in the present embodiment, after the additional step of the silicon raw material, a cleaning step in the chamber 10 using the dummy ingot 50 is performed.

In the cleaning step, the empty input pipe 60 attached to the lower end of the wire rope 17 is removed and replaced with the dummy ingot 50, and then the dummy ingot 50 is lowered to the vicinity of the melt surface as shown in fig. 9. At this time, it is preferable that the quartz crucible 12 is also lowered as much as possible. That is, the height of the quartz crucible 12 is adjusted so that the height position of the quartz crucible 12 at the start of the cleaning step is lower than the height position of the quartz crucible 12 at the start of the single crystal pulling step.

Fig. 9 shows a state in which the quartz crucible 12 and dummy ingot 50 have been sufficiently lowered to start the cleaning process. In addition, the state during the cleaning process may be such a state. In this manner, in the lowered position of the dummy ingot 50, the lower end of the shoulder portion 50a (the upper end of the body portion 50 b) of the dummy ingot 50 is preferably disposed below the lower end of the thermal shield 16. By raising the dummy ingot 50 located at this position, the same situation as when the silicon single crystal 2 is gradually pulled from the silicon melt 3 can be reproduced.

Fig. 7 shows a state in which the quartz crucible 12 and dummy ingot 50 are raised higher than the position shown in fig. 9. The lower end of the shoulder 50a of the dummy ingot 50 becomes exactly the same height position as the lower end of the heat shield 16. This is the same as the state shown in fig. 4 (b). In the actual single crystal pulling step, when the shoulder portion of the silicon single crystal is positioned close to the lower end of the heat shield 16, the flow of the gas is rapidly increased, and the crystal is likely to be disturbed. In the present embodiment, since this situation can be reproduced, a turbulent flow is generated in the chamber 10, and foreign matter such as fine silicon powder can be removed.

As shown in the drawing, when the lower end of the shoulder portion 50a of the dummy ingot 50 is the same height as the lower end of the heat shield 16, the gap width (1 st gap width) between the liquid level of the silicon melt 3 and the lower end of the heat shield is preferably adjusted as follows: the gap width (2 nd gap width) between the liquid surface of the raw material melt and the lower end of the heat shield in the actual single crystal pulling step is substantially equal to that which can be used in the actual single crystal pulling. By setting in this manner, the same situation as in the actual single crystal pulling step can be reproduced. That is, since not only the lateral gap between the heat shield 16 and the dummy ingot 50 is narrowed but also the longitudinal gap between the heat shield 16 and the melt surface is narrowed, the flow velocity of the argon gas trying to pass through the narrow gap between the heat shield 16 and the dummy ingot 50 is further increased, and the gas flow in the chamber 10 is changed, and the turbulent flow is easily generated.

A state in which the dummy ingot 50 is further raised is shown in fig. 10. In this case, as in fig. 6, foreign matters in the sub-chamber 10B can be removed, and the occurrence rate of dislocation of the single crystal due to adhesion of foreign matters can be reduced.

The quartz crucible 12 may be moved up and down together with the dummy ingot 50 in the movement of moving up and down. When the dummy ingot 50 is moved up and down below the lower end of the thermal shield 16, the quartz crucible 12 is moved up and down in accordance with the up-and-down movement, whereby the dummy ingot 50 can be placed at an appropriate position without the dummy ingot 50 coming into contact with the silicon melt 3, and the gap width (1 st gap width) between the lower end of the thermal shield 16 and the silicon melt 3 can be made close to the gap width (2 nd gap width) in the actual pulling step.

As described above, the cleaning method by the single crystal pulling apparatus 1 according to the present embodiment also reproduces the structure in the chamber during pulling of a single crystal, and by artificially creating a strong flow and turbulence of argon gas generated in the chamber due to the presence of the quartz crucible and the single crystal ingot, the flow rate of the inert gas is intentionally changed to detach and remove foreign matter such as fine silicon powder adhering to the chamber in advance, so that the amount of dust generation in the subsequent pulling step can be reduced, and the rate of occurrence of dislocation of a single crystal due to adhesion of foreign matter can be reduced.

While the preferred embodiments of the present invention have been described above, it is obvious that the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, in the above embodiment, the dummy crucible 30 and the dummy ingot 40 are used together for cleaning, but cleaning may be performed using only the dummy crucible 30 or cleaning may be performed using only the dummy ingot 40.

In the above embodiment, the material of the dummy crucible 30 and the dummy ingot 40 is a resin, but the material of the dummy crucible 30 and the dummy ingot 40 in the present invention is not limited to a resin, and for example, a carbon material may be used.

As described above, the shapes of the dummy crucible 30 and

dummy ingots

40 and 50 are not particularly limited as long as they are substantially similar to each other, and the degree of similarity is not particularly limited as long as the effects of the invention can be exerted. Therefore, for example, the dummy crucible 30 may be provided with a notch or may be eccentric. The

dummy ingots

40 and 50 may be elliptical cylinders other than right circular cylinders, may have irregularities on the outer circumferential surfaces of circular cylinders, or may have a twisted shape of a crystal habit line. Even when the dummy crucible 30 and

dummy ingots

40 and 50 are different in shape from the actual ones, the inside of the chamber can be cleaned by the flow of the gas, and the cleaning effect can be promoted by the increase of turbulence.

In the above embodiment, argon is used as the gas to be supplied into the chamber, but other inert gas may be used instead of argon, or air may be used.

In the above-described embodiment, the silicon single crystal pulling apparatus is exemplified, but the present invention is not limited thereto, and various single crystal pulling apparatuses such as SiC and sapphire can be used. However, although SiO evaporated from a silicon melt is likely to adhere to the inside of a chamber in the production of a silicon single crystal for semiconductor by the CZ method, the present invention is preferably applicable to cleaning of a pulling apparatus used in the production of a silicon single crystal for semiconductor by the CZ method from the viewpoint that it is difficult to disassemble and clean each corner in the chamber because the apparatus is large in size.

Description of the reference numerals

1-single crystal pulling apparatus, 2-silicon single crystal, 3-silicon melt, 5-additional silicon raw material, 10-chamber, 10A-main chamber, 10B-sub-chamber, 11-heat insulating material, 12-quartz crucible, 13-base, 14-rotating support shaft, 15-heater, 16-heat shield, 16 a-opening, 17-wire rope, 17 a-hook, 18-take-up mechanism, 19A-air inlet, 19B-air outlet, 30-dummy crucible, 31-dummy liquid level, 32-dummy ingot (1 st dummy ingot), 32 a-projection of dummy ingot, 40-dummy ingot (2 nd dummy ingot), 40A-shoulder of dummy ingot, 40B-body of dummy ingot, 40 c-recess of dummy ingot, 40 d-ring fitting, 50-dummy ingot, 60-input tube.

Claims

1. A method for cleaning a single crystal pulling apparatus, comprising the following cleaning steps:

a dummy crucible is prepared which includes a dummy liquid surface which is a surface of a raw material melt in the crucible and a 1 st dummy ingot which is a surface of a single crystal ingot pulled upward from the surface of the raw material melt, and a gas is supplied in a depressurized chamber of a single crystal pulling apparatus, and the gas is flowed under the influence of the dummy crucible, so that foreign substances attached to a wall surface of the chamber or components in the chamber are removed.

2. The cleaning method according to claim 1,

the single crystal pulling apparatus includes:

a rotary support shaft that supports the crucible in the chamber so as to be able to ascend and descend; and

a heat shield disposed above the rotation support shaft,

the cleaning step is performed by adjusting the height of the dummy crucible so that a 1 st gap width between the dummy liquid surface and the lower end of the heat shield is substantially equal to a 2 nd gap width between the liquid surface of the raw material melt and the lower end of the heat shield in an actual single crystal pulling step.

3. The cleaning method according to claim 1 or 2,

in the cleaning step, the dummy crucible is swung up and down.

4. The cleaning method according to claim 1 or 2,

the dummy crucible is made of resin.

5. The cleaning method according to claim 2,

preparing a 2 nd dummy ingot imitating a single crystal ingot, and in the cleaning step, supplying the gas in a state where the 2 nd dummy ingot is suspended in the chamber, and generating a flow of the gas affected by the 2 nd dummy ingot to detach foreign matter adhering to a wall surface of the chamber or a component in the chamber.

6. The cleaning method according to claim 5,

the cleaning step is performed in a state where the 2 nd dummy ingot and the 1 st dummy ingot are connected to each other.

7. The cleaning method according to claim 5,

the chamber has:

a main chamber; and

a sub-chamber connected to an upper opening of the main chamber,

the cleaning step is performed in a state where the 2 nd dummy ingot is disposed in the sub-chamber.

8. The cleaning method according to claim 7,

the cleaning step is performed in a state in which the 2 nd dummy ingot is vertically swung independently of the dummy crucible.

9. The cleaning method according to claim 5,

the single crystal pulling apparatus further includes a wire rope disposed coaxially with the rotation support shaft and having a hook attached to a distal end portion thereof,

a ring fitting is mounted on a tip end portion of the 2 nd dummy ingot,

the 2 nd dummy ingot is coupled to the lower end portion of the wire rope by engaging the hook with the ring fitting and by allowing the engagement to take a play.

10. The cleaning method according to any one of claims 5 to 9,

the 2 nd dummy ingot is made of resin.

11. A method for cleaning a single crystal pulling apparatus, comprising the following cleaning steps:

a dummy ingot which is a single crystal ingot is prepared, and a gas is supplied in a state where the dummy ingot is placed in a depressurized chamber of a single crystal pulling apparatus, and a flow of the gas affected by the dummy ingot is generated to detach foreign matter adhering to a wall surface of the chamber or components in the chamber.

12. The cleaning method according to claim 11,

the cleaning process is performed in a state where the dummy ingot is swung up and down.

13. The cleaning method according to claim 11 or 12,

the dummy ingot is made of resin.

14. The cleaning method according to claim 11 or 12,

the cleaning step is performed with the temperature in the chamber set to a normal temperature.

15. The cleaning method according to claim 11 or 12,

the dummy ingot has:

a shoulder portion having a gradually increasing diameter; and

a body portion having a constant diameter below the shoulder portion,

in the cleaning step, the dummy ingot is pulled up so that a lower end of the shoulder portion passes through an opening at a lower end of a heat shield provided in the chamber.

16. The cleaning method according to claim 11 or 12,

the chamber has:

a main chamber; and

a sub-chamber connected to an upper opening of the main chamber,

the cleaning step is performed in a state where the dummy ingot is disposed in the sub-chamber.

17. The cleaning method according to claim 11,

the method includes the steps of disposing a crucible that supports the raw material melt in the chamber, and performing the cleaning process in the chamber at a high temperature in which the raw material melt is actually stored in the crucible.

18. The cleaning method according to claim 17,

19. The cleaning method according to claim 17 or 18,

the dummy ingot has:

a shoulder portion having a gradually increasing diameter; and

a body portion having a constant diameter below the shoulder portion,

in the cleaning step, the dummy ingot is pulled up so that a lower end of the shoulder portion passes through an opening in a lower end of a heat shield provided above the crucible.

20. The cleaning method according to claim 19,

the height of the crucible is adjusted so that the height of the crucible at the start of the cleaning step is lower than the height of the crucible at the start of the single crystal pulling step.

21. The cleaning method according to claim 19,

when the lower end of the shoulder portion is at the same height as the lower end of the heat shield in the cleaning step, the height of the crucible is adjusted so that a 1 st gap width between the liquid surface of the raw material melt and the lower end of the heat shield is substantially equal to a 2 nd gap width between the liquid surface of the raw material melt and the lower end of the heat shield in an actual single crystal pulling step.

22. The cleaning method according to claim 17 or 18,

the cleaning step is performed after the raw material is additionally charged into the crucible.

23. The cleaning method according to claim 22,

the method for cleaning a single crystal includes the steps of additionally charging the raw material using a charging pipe connected to a lower end of a pulling shaft for pulling the single crystal, replacing the charging pipe with the dummy ingot, and performing the cleaning step.

24. The cleaning method according to claim 17 or 18,

the crucible is made of quartz and is provided with a plurality of holes,

the dummy ingot is made of at least one material selected from the group consisting of silicon, quartz, carbon, silicon carbide, and molybdenum.

25. The cleaning method according to claim 17 or 18,

the dummy ingot has a hollow structure.

26. A cleaning tool for a single crystal pulling apparatus, comprising:

a dummy crucible which simulates a crucible used in pulling of a single crystal;

a dummy liquid level which is a level of the raw material melt in the crucible; and

and (1) a dummy ingot which is a single crystal ingot pulled upward from the liquid surface of the raw material melt.

27. The cleaning appliance of claim 26 wherein,

the cleaning tool further comprises a No. 2 dummy ingot imitating the single crystal ingot,

the upper end portion of the 1 st dummy ingot has a convex portion of a conical shape,

a lower end portion of the 2 nd dummy ingot has a conical recess into which the upper end portion of the 1 st dummy ingot can be fitted.

28. A cleaning tool for a silicon single crystal pulling apparatus is characterized in that,

is composed of a dummy ingot imitating a single crystal ingot,

the dummy ingot has a recess having a conical shape at a lower end portion thereof.

29. A method for producing a single crystal, comprising:

disassembling and cleaning a chamber of a single crystal pulling apparatus and components in the chamber;

a step of performing final cleaning of the single crystal pulling apparatus by the cleaning method according to any one of claims 1 to 25 after the detachment cleaning; and

and pulling up the single crystal by using the single crystal pulling apparatus after the final cleaning is finished.